mlxsw: spectrum: Properly cleanup LAG uppers when removing port from LAG

When a LAG device or a VLAN device on top of it is enslaved to a bridge,
the driver propagates the CHANGEUPPER event to the LAG's slaves.

This causes each physical port to increase the reference count of the
internal representation of the bridge port by calling
mlxsw_sp_port_bridge_join().

However, when a port is removed from a LAG, the corresponding leave()
function is not called and the reference count is not decremented. This
leads to ugly hacks such as mlxsw_sp_bridge_port_should_destroy() that
try to understand if the bridge port should be destroyed even when its
reference count is not 0.

Instead, make sure that when a port is unlinked from a LAG it would see
the same events as if the LAG (or its uppers) were unlinked from a
bridge.

The above is achieved by walking the LAG's uppers when a port is
unlinked and calling mlxsw_sp_port_bridge_leave() for each upper that is
enslaved to a bridge.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum.c

@@ -4498,6 +4498,25 @@ void mlxsw_sp_port_dev_put(struct mlxsw_sp_port *mlxsw_sp_port)
 	dev_put(mlxsw_sp_port->dev);
 }
 
+static void
+mlxsw_sp_port_lag_uppers_cleanup(struct mlxsw_sp_port *mlxsw_sp_port,
+				 struct net_device *lag_dev)
+{
+	struct net_device *br_dev = netdev_master_upper_dev_get(lag_dev);
+	struct net_device *upper_dev;
+	struct list_head *iter;
+
+	if (netif_is_bridge_port(lag_dev))
+		mlxsw_sp_port_bridge_leave(mlxsw_sp_port, lag_dev, br_dev);
+
+	netdev_for_each_upper_dev_rcu(lag_dev, upper_dev, iter) {
+		if (!netif_is_bridge_port(upper_dev))
+			continue;
+		br_dev = netdev_master_upper_dev_get(upper_dev);
+		mlxsw_sp_port_bridge_leave(mlxsw_sp_port, upper_dev, br_dev);
+	}
+}
+
 static int mlxsw_sp_lag_create(struct mlxsw_sp *mlxsw_sp, u16 lag_id)
 {
 	char sldr_pl[MLXSW_REG_SLDR_LEN];
@@ -4690,6 +4709,10 @@ static void mlxsw_sp_port_lag_leave(struct mlxsw_sp_port *mlxsw_sp_port,
 
 	/* Any VLANs configured on the port are no longer valid */
 	mlxsw_sp_port_vlan_flush(mlxsw_sp_port);
+	/* Make the LAG and its directly linked uppers leave bridges they
+	 * are memeber in
+	 */
+	mlxsw_sp_port_lag_uppers_cleanup(mlxsw_sp_port, lag_dev);
 
 	if (lag->ref_count == 1)
 		mlxsw_sp_lag_destroy(mlxsw_sp, lag_id);

drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c

@@ -290,30 +290,6 @@ mlxsw_sp_bridge_port_destroy(struct mlxsw_sp_bridge_port *bridge_port)
 	kfree(bridge_port);
 }
 
-static bool
-mlxsw_sp_bridge_port_should_destroy(const struct mlxsw_sp_bridge_port *
-				    bridge_port)
-{
-	struct net_device *dev = bridge_port->dev;
-	struct mlxsw_sp *mlxsw_sp;
-
-	if (is_vlan_dev(dev))
-		mlxsw_sp = mlxsw_sp_lower_get(vlan_dev_real_dev(dev));
-	else
-		mlxsw_sp = mlxsw_sp_lower_get(dev);
-
-	/* In case ports were pulled from out of a bridged LAG, then
-	 * it's possible the reference count isn't zero, yet the bridge
-	 * port should be destroyed, as it's no longer an upper of ours.
-	 */
-	if (!mlxsw_sp && list_empty(&bridge_port->vlans_list))
-		return true;
-	else if (bridge_port->ref_count == 0)
-		return true;
-	else
-		return false;
-}
-
 static struct mlxsw_sp_bridge_port *
 mlxsw_sp_bridge_port_get(struct mlxsw_sp_bridge *bridge,
 			 struct net_device *brport_dev)
@@ -351,8 +327,7 @@ static void mlxsw_sp_bridge_port_put(struct mlxsw_sp_bridge *bridge,
 {
 	struct mlxsw_sp_bridge_device *bridge_device;
 
-	bridge_port->ref_count--;
-	if (!mlxsw_sp_bridge_port_should_destroy(bridge_port))
+	if (--bridge_port->ref_count != 0)
 		return;
 	bridge_device = bridge_port->bridge_device;
 	mlxsw_sp_bridge_port_destroy(bridge_port);